## Summary
In this pull request we're removing `agent_name` from subdomains in APP
urls when an `app` is used in the subdomain. `agent_names` will still be
used when a `port` is used in the subdomain.
Closes: https://github.com/coder/coder/issues/18485
### Changes
- Updated regex to support an optional agent name
- Added logic to support checking the app slug for a matching port
(e.g., 8080 or 8080s)
### Testing
- Updated all tests to support an optional `agent_name`